Use of Japanese-beetle traps to monitor flight of the Pacific coast wireworm, Limonius canus (Coleoptera: Elateridae), and effects of trap height and color

Abstract

Japanese-beetle traps were used to monitor flight of the Pacific coast wireworm, Limonius canus LeConte, in an agricultural field in northern Oregon. Overwintered beetles first appeared in traps in mid-March 2000 and 2001, and were collected until mid- to late-May both years. Most (93%) of the females collected at the beginning of the flight period had been in seminated, which may indicate that mating takes place very soon after beetles emerge from the soil. Sex ratios favored males at the beginning of the flight period and favored females at the end of the flight period. Lower temperatures in April 2001 compared to those in 2000 may have caused a delay in timing of the peak catch (relative to timing in 2000) by almost 3 weeks. A count of over eight beetles per trap per 7-day sampling interval was obtained during the week of peak catch in April 2000. Traps were hung at three heights: 1.5, 0.9, and 0.3 m above ground. Catch decreased with increasing trap height. Traps that had been painted yellow collected more beetles than traps painted white, which in turn collected more beetles than traps painted red, green, dark blue, or black. Two other elaterids, Ctenicera pruinina (Horn) and Cardiophorus montanus Bland, were also trapped during the study.

Key words: Limonius canus; click beetles; monitoring; flight; trap